Touch-sensitive displays have become commonplace in today's electronic devices. For example, many of today's cellular telephones, mp3 players, laptops, office equipment, ATM machines, credit card readers, and even kitchen electronics include touch-sensitive displays that both communicate visual information and allow a user to actuate device functions via touch based commands communicated through interaction with the display.
A typical touch-sensitive display device includes a matrix of LED (light-emitting diode) elements. These elements may be selectively activated by controller circuitry to portray images on the display. Other touch-sensitive display devices include liquid crystal displays (LCDs), plasma and the like.
Known touch-sensitive display devices also include touch sense elements operable to detect one or more objects, such as a finger or stylus, at or near a display, and communicate information related to object detection to a controller for processing. The controller may then operate functions of the display device based on the received information.
One typical type of touch sense element is a capacitive touch sense element. Generally speaking, whenever two electrically conductive members come in proximity with one another, their respective electric fields interact and cause a measurable capacitance. A capacitive touch sense element is constructed to detect capacitance formed at or near (e.g. an edge of a display) a surface of a display by the placement of a finger or stylus in proximity or contact with the screen. Many other technologies also enable touch-sensitive actuation of a display, including: resistive, infrared, surface acoustic wave, electromagnetic, and near field imaging technologies, among others.
As previously mentioned, many known touch-sensitive display devices incorporate some form of an electronic controller to operate LED elements, touch sense elements, or other functions. Typically, such a controller is provided in the form of an Integrated Circuit (IC) device, for example a device that includes an Application Specific Integrated Circuit (ASIC) or a Field Programmable Gate Array (FPGA). Such an IC device typically includes at least one semiconductor die provided in an IC package. The die includes a multitude of interconnected IC components such as transistors, capacitors, resistors, and the like that make up the electrical circuits of the IC. The IC package includes multiple input/output (I/O) pins that allow electrical connection to these circuits to enable functions of the die to be utilized. One significant limitation on the usefulness of an IC device is that, in order to meet size requirements, many ICs present a limited number of I/O pins at an exterior of the device.
Known touch-sensitive LED devices require at least one dedicated I/O pin of an IC-based controller to control each of LED and touch sense operations. As such, there is a need for improvements in touch-sensitive LED display devices.